1. Field of the Invention
The present technology relates to an image processing device, an image processing method, and a recording medium.
2. Description of the Related Art
An image can be divided broadly into a flat potion, an edge potion and a texture portion. The flat portion is a region in the image having a small local luminance change while the edge portion is a region in the image having a large local luminance change. The texture portion is a region in the image having a luminance change in a relatively broad area, the luminance change not being so large as that of the edge portion.
A general impression of the image is determined according to the texture portion. When the texture portion included in a region in the image has a large luminance change, the image has a relatively rough impression, while when the texture portion included in a region in the image has a small luminance change, the image has a relatively smooth impression. Therefore, the general impression of the image can be controlled if the luminance change in the texture portion can be operated on.
A technology for improving sharpness of an image by emphasizing portions of the image other than the edge portion is known (for example, Japanese Patent Gazette No. 4415236). Specifically, in generating a differential image between an input image and a smoothed image which has been generated by performing an edge preserving smoothing process on the input image, the differential image is multiplied by a gain coefficient. Then, a consequent image, in which contrast or sharpness of the whole image is improved, is generated by adding the image multiplied by the gain coefficient to the smoothed image.
However, in the prior art described above, a user cannot easily operate an intensity of the texture portion as the user desired. That is, in the prior art described above, the method for dynamically determining the gain coefficient according to property of an input image is not disclosed, while the gain coefficient is set as a predetermined value for the whole image or set as values for respective pixels in the image, wherein the gain coefficient is to be determined according to an object of a correction, positions of the pixels, texture intensity or the like.